Functional syndromes (FS) are illnesses characterized by constellations of symptoms, suffering, and disability that cannot be explained by an evidence-based pathophysiologic mechanism. Functional syndromes, such as chronic fatigue syndrome, fibromyalgia, interstitial cystitis (IC), and irritable bowel syndrome are among the most common reasons human beings seek medical care. Physicians generally adopt a symptomatic empirical approach for these conditions. They are important causes of chronic illness and healthcare utilization, because patients often do not get better as a result of currently available therapies.
Patients with FS are seen by all medical specialties. IC is one of the most common FS in urology. IC is characterized by chronic pain, excessive urgency and frequency of urination, nocturia, and negative urine cultures. As many as 750,000 women in the United States may suffer from IC. Data from the Nurses' Health Study suggests that the prevalence of IC among women is about 52-67 per 100,000. Patients often reach a diagnosis of IC through an emotionally charged and difficult route, the product of numerous physician encounters and stigmatizing experiences. IC interferes with employment, social relationships and sexual activity. The chronic pain, frequency, urgency and sleep deprivation associated with IC may contribute to psychological stress and secondary depression. Chronic bladder and pelvic pain is usually moderate to severe in patients with IC; more than one half of symptomatic patients also suffer from depression, and suicidal ideation is 3-4 times more common in these patients than in the general population.
Diagnosing FS is difficult. One of the reasons for this is that there may be a variety of nonspecific symptoms associated with the FS. Before a diagnosis of IC can be made, for example, many non-related conditions and disorders (urinary tract infections, vaginal infections (in women), chronic prostatitis (in men), bladder cancer, bladder inflammation or infection, kidney stones, endometriosis, neurological disorders, sexually transmitted diseases among other) must be ruled out. Currently there is no well accepted diagnostic test for many functional syndromes like IC. It is therefore an unmet advantage of the prior art to provide a simple, rapid, and reliable method to diagnose functional disorders such as IC. A similar syndrome, called feline IC (FIC), is the most common lower urinary tract disorder of domestic cats.